Particle tracking velocimetry and trajectory curvature statistics for particle-laden liquid metal flow in the wake of a cylindrical obstacle

TL;DR

This study advances particle tracking velocimetry in liquid metal flows using neutron radiography, improving accuracy and enabling detailed analysis of turbulence, vortex shedding, and particle trajectories around obstacles.

Contribution

We developed an improved particle tracking method with divergence-free interpolation, enhancing analysis of turbulent liquid metal wake flows and validating results against theoretical and experimental data.

Findings

Accurate vortex shedding frequency scaling with Reynolds number

Identification of universal algebraic growth laws in trajectory curvature

Physically consistent particle residence time and velocity statistics

Abstract

This paper presents the analysis of the particle-laden liquid metal wake flow around a cylindrical obstacle at different obstacle Reynolds numbers. Particles in liquid metal are visualized using dynamic neutron radiography. We present the results of particle tracking velocimetry of the obstacle wake flow using an improved version of our image processing and particle tracking code MHT-X. The latter now utilizes divergence-free interpolation of the particle image velocimetry field used for motion prediction and particle trajectory reconstruction. We demonstrate significant improvement over the previously obtained results by showing the capabilities to assess both temporal and spatial characteristics of turbulent liquid metal flow, and validating the precision and accuracy of our methods against theoretical expectations, numerical simulations and experiments reported in literature. We obtain the expected vortex shedding frequency scaling with the obstacle Reynolds number and correctly identify the universal algebraic growth laws predicted and observed for trajectory curvature in isotropic homogeneous two-dimensional turbulence. Particle residence times within the obstacle wake and velocity statistics are also derived and found to be physically sound. Finally, we outline potential improvements to our methodology and plans for further research using neutron imaging of particle-laden flow.